1. Field of the Invention
The present invention relates to a shear deformation device for shearing materials, generally, metal materials, and more particularly, to a shear deformation device capable of shearing and at the same time scalping the materials at a predetermined thickness.
2. Description of the Background Art
The shear deformation process is a process of obtaining a sheared material by passing a material into a mold for shear deformation having a molding path at which a curved portion is formed, and allowing shear deformation of the material to occur at the curved portion. This process has the object of fabricating a material of high strength and high plasticity by improving the strength of the material and forming a texture having a certain direction.
The above-mentioned shear deformation processes includes equal channel angular pressing (ECAP), equal channel angular drawing (ECAD), continuous ECAP process, and so on. FIGS. 1a, 1b and 2 are views schematically illustrating shear deformation devices performing these shear deformation processes, respectively. As illustrated therein, the shear deformation devices are identical with one another in that each shear deformation device is constructed of molds 1, 2, 6, and 7 provided with molding paths 3 and 8 having a curved portion shown in dotted line, but they are different from one another with respect to a means for applying power in order to passing materials 5 and 9 through the molds 3 and 8.
Among these shear deformation processes, in case of equal channel angular pressing, only a sheared material of a limited length is obtained. Once the material is scalped, the next material can be provided only after extracting a punch 4 from the molds 1 and 2, so it is impossible to continuously mass-producing sheared materials. In case of equal channel angular drawing, although it is possible to mass-produce sheared materials, it is difficult to practically use this process because it has little effect for shear deformation. For the continuous mass production of materials having an appropriate amount of shear deformation, a continuous shear deformation device illustrated in FIG. 2 which uses rotary guide apparatuses 10 and 11 in place of the punch 4 in order to continuously perform equal channel angular drawing is suitable.
However, in order to achieve shear deformation as the material implanted into the mold passes through the curved portion, much power is needed. Therefore, in case of using the rotary guide apparatuses 10 and 11, it is general that irregularity is formed on the surface in contact with the material of the rotary guide apparatuses 10 and 11 in order to increase the friction between the material and the rotary guide apparatuses 10 and 11. Subsequently, irregularity corresponding the above irregularity is formed on the surface of the material 9 having passed through the molds 6 and 7 for thereby making the surface rough.
In addition, even though the rotary guide apparatus is not used, there may be formed undesirable surface products on the surface of the material by material finishing processes prior to putting the material into the shear deformation device, that is, rolling and casting.
Meanwhile, in the conventional shear deformation device described above, there is a problem that the materials 5 and 9 cannot be tightly attached to the lower molds 2 and 7, and thus the amount of shear deformation in the lower parts of the materials 5 and 9 becomes insufficient. FIG. 3 is a view illustrating the deformation of a material at a curved portion of a mold by simulation. By this, it is known that a board plank is not completely attached to a molding surface at the curved portion directed by an arrow, but is isolated therefrom. Accordingly, it is known that the amount of shear deformation in the lower portions of the material is not sufficient as compared to other portions, which is confirmed by an actual experiment performed by the inventors. That is, the scales indicated in a vertical direction on the sides prior to shear deformation of the material as shown in FIG. 4a are indicated as shown in FIG. 4b after passing through the continuous shear deformation device, which indicates that the amount of shear deformation in the lower portions of the material is smaller than that in other portions.
In addition, in the conventional discontinuous or continuous shear deformation devices described above, a curved portion is formed at the center of molding path 3 and 8 having the same widths, and thus the movement of the materials 5 and 9 is inhibited by the friction at the molding path excepting the curved portion at which shear deformation is actually occurred. Therefore, a considerable power plus the power required for shear deformation in the curved portion has to be additionally applied to the materials, which is ineffective.
In addition, there is another problem that the life span of the molds is not long because the abrasion occurred adjacent the curved portion which receives the largest friction force from the molds 3 and 8 is rapidly performed as compared to other portions.
Accordingly, the objects of the present invention disclosed to overcome the problems encountered in the conventional art will be described.
It is an object of the present invention to provide a shear deformation device capable of shearing material and at the same time removing irregularity or surface products formed on the surface of the material.
It is another object of the present invention to provide a continuous shear deformation device capable of obtaining an uniform and sufficient amount of shear deformation throughout the material by assuring contact between a lower part of the material and a curved portion in a molding path at which the material is sheared.
It is another object of the present invention to provide a continuous shear deformation device capable of press-fitting the material by small power as the friction between the portions of the molding path excepting the curved portion and the material is reduced.
It is another object of the present invention to provide a continuous shear deformation device capable of assuring a longer life span of the mold.
It is another object of the present invention to provide a continuous shear deformation device which can be compatibly used in response to materials of different thickness, that is, from thin-walled materials to thick-walled materials.
To achieve the above objects, there is provided a shear deformation device capable of scalping in accordance with the present invention which includes a mold having a molding path at which a curved portion is formed; and a material guiding apparatus for guiding a material to the molding path, wherein a scalping guide path which allows the surface of the material to be separated from the other portions of the material as the material is scalped at a predetermined thickness when passing through the curved portion during shear deformation is formed in the curved portion in communication with the molding path.
The above-mentioned shear deformation device can be a device performing a discontinuous equal channel angular pressing, a device performing a continuous shear deformation, or a device performing an equal channel angular drawing. In case of the discontinuous equal channel angular pressing, a punch corresponds to the guiding apparatus, and in case of the continuous shear deformation device, a rotary guide apparatus is used as the guiding apparatus.
In this case, since the thickness at which the material is scalped is determined according to the inner spacing of the scalping guide path, the scalping guide path can be formed to have a fixed inner spacing. However, in order to scalp the material at a desired thickness, it is preferable that a spacing adjusting apparatus for adjusting the inner spacing of the scalping guide path is additionally included.
As the rotary guide apparatus, a rotary roll contacting materials, or a belt transmission for moving materials by rotating a belt contacting the materials can be used. As the belt, belts of various shapes, such as a roof having a plurality of polyhedron blocks sequentially connected to the same and a belt of which the inside is chain-shaped, can be used. In addition, the rotary guide apparatus can be a combination of the rotary roll and the belt transmission. For example, the rotary guide apparatus can be constructed by installing a plurality of rotary rolls at one side and a belt transmission at the other side. Also, in case of using the belt transmission, it is possible to use a combination of belts of various shapes.
To reinforce the friction between the material and the rotary guide apparatus, it is preferable that irregularity is formed on the surface contacting the material of the rotary guide apparatus, that is, the surface of the rotary roll or the belt. This is achieved by coating the surface using an additional material of high friction coefficient, or by increasing the surface roughness by forming irregularity by mechanical processing. In addition, it is also possible to fabricate a portion directly contacting the material throughout the entire rotary guide apparatus by using a material of high friction coefficient.
The curved portion in the molding path can be formed at the center of the molding path as in the conventional art. Preferably, in order to reinforce the contact between the lower part of the material and the curved portion, the curved portion is constructed by collaboration between the rotary guide apparatus and the opening of the molding path, and the separation between the rotary guide apparatus and the mold constructs the scalping guide path.
And, it is preferable that a lateral guide for guiding and supporting the lateral parts of the material is installed at the rotary guide apparatus in order to prevent the material from being bilaterally moved while passing through the mold for the purpose of shear deformation. Such a lateral guide can be installed at one of the rotary guide apparatus and the mold, or at both of them.
In addition, it is preferable to construct the continuous shear deformation device by installing the rotary guide apparatus and the mold as one part of a continuous processing equipment, in order to perform shear deformation as one process step in a continuous process for processing the material by means of multiple process steps. For example, the material can be heated at a desired temperature, and then can be sheared. In this case, it is possible to connect the continuous shear deformation device to an apparatus for heating the material. In a case where a cast or rolled material is directly sheared, the continuous shear deformation device can be connected to a continuous casting apparatus or a rolling apparatus. In addition, the continuous shear deformation device can be connected to an apparatus for cooling, cutting, flattening, or winding the material extracted from the continuous shear deformation device.
With respect to this, the thickness of the material before passing through the rotary guide apparatus may be larger than the thickness of the material after passing through the same. For example, it can be assumed that the rotary guide apparatus is constructed by using a series of pairs of rotary rolls, the spacing between which being gradually reduced. In this case, it is possible to provide a compatible continuous shear deformation device to materials of different thickness, for example, thin-walled materials of a thickness less than 0.5 mm and thick-walled materials, irrespective of thickness of the materials, by rolling the materials corresponding to the clearance spacing of a material supply path having gradually reduced widths formed by the rotary guide apparatus, without any additional processing of the materials.
It is natural that the amount of shear deformation of the material is adjusted according to the angle of the curved portion. Moreover, it is also possible to additionally form one or more curved portions at the molding path of the mold besides the curved portion at the opening, so that the material is sheared more than two times while passing through the molding path.
Friction is most apparent in the vicinity of the curved portion in the mold at which shear deformation is occurred. Thus, in order to improve the abrasion resistance of the vicinity of the curved portion, it is possible to fabricate that portion using an ultralight material. At this time, the vicinity of the curved portion can be coated with the ultralight material, or it can be entirely made of the ultralight material.
In addition, some part including the curve portion in the mold, which is greatly abraded during shear deformation, can be constructed as a separate, replaceable component.
In order to reduce the power applied in the direction of the material by decreasing the friction between the mold and the material, it is preferable that a lubricant applicator is additionally included.
As another construction for reducing friction force, it is preferable that the widths of the molding path before the curved portion are formed to be larger than those of the molding path behind the curved portion, centering around the point spaced apart at a certain distance via the curved portion in the direction of the material, thereby reducing unnecessary friction between the material and the molding path.
Although the widths of the molding path before the curved portion are identical with those of the molding path behind the curved portion in general, it is also possible to design and fabricate a mold of which the widths of the molding path before and behind the curved portion are different from each other, so that the thickness of the material before shear deformation is different from that of the material after shear deformation.